Tunable ultra-broadband multi-band NIR emission in Bi-doped aluminogermanate glasses and fibers via controllable Al2O3 content for broadband amplifiers

Abstract

Bismuth (Bi)-doped glasses with broadband near-infrared (NIR) emission have been drawing increasing interest due to their potential applications in tunable fiber lasers and broadband optical amplifiers. Yet, the realization of highly efficient and ultra-broadband Bi NIR emission covering the whole telecommunication window remains a daunting challenge. Here, via rationally controlling the content of Al₂O₃ to control the local environment and structural defect states around the Bi NIR active centers (BACs), various luminescence centers can coexist stably in a glass matrix. Consequently, tunable ultra-broadband multi-band NIR emission with four emission bands at ∼924, ∼1154, ∼1265, and ∼1516 nm was achieved in a Bi-doped germanate glass under single wavelength excitation. More importantly, such ultra-broadband multi-band Bi NIR emission with excellent thermal stability can be well retained after the glass was drawn into an optical fiber by a rod-in-tube method. The fibers show an obvious broadband ASE spectrum spanning a range of 1000–1600 nm. This work is helpful for understanding the mechanism of Bi NIR emission and offers a simple and feasible method for developing novel photonic devices with ultra-broadband Bi NIR emission.